Pump



G. J. TRA PP PUMP 2 sHEETs-SHEET 1 Dec. 16, 1952 Fild Dec. 51.'1947Inven'b 01" Dec. 16, 1952 G J, TRAPP 2,621,607

PUMP Filed DeC- 51. 1947 2 SHEETS-SHEET 2 Imrntr Grg, J Tm?? Ati ofneysPatented Dec. 16, 1952 UNITEDSTATES PATENT OFFICE PUMP George JosephTrapp, Leamington Spa, England Application December 31, 1947, Serial No.795,042 In Great Britain January 3, 1947 11 Claims. 1

This invention relates to reciprocating pumps With radial cylindershaving the pistons operated b'y a'rotary era-nk shaft, eccentric shaftor eccentric track.

The invention has for its main object to provide an improved pump ofthis character capable of operatingrcontinuously at high speed andpressure with a relatively low weight per horse power, the pump beingespecially suitable for use on aircraft in the supply of pressure liquidfor actuatingV various accessory mechanisms, for example i landingcarriages.

An importantI object of the invention is to provide a pump of theabove-mentioned Character, having the inlet to each cylinder controlledby the piston uncovering a port in the cylinder wall and the outlettaking place through a non-return or delivery valve, and having separatecylinders detachably mounted in the pump body, in which improved meansfor mounting the cylinders serve to locate them in their correctpositions and at the same time to transmit to the pump body the thrustdue to the pumping action. I

A specificl object is to provide a pump of this character in which eachcylinder has its nonreturn valve seat formed integrally With it upon aspigot-likeprojection from the side of the cylinder, the severalprojections being adapted for engagement in holes or sockets in the pumpbody.

Another object of the invention is to provide a pump of this characterin which the pump body has a, Adetachable cover fitting over thecylinders, the presence of the cover ensuring the looking of the meansemployed for clamping the cylinders in place,.so that no loosening cantake place due to vibration during operation of the pump.

Other Vobjects and advantages of the invention will hereinafter appearfrom the following description of a preferred embodiment, given withreference to the accompanying drawings, in which:

Fig. 1 is a sectional elevation of the pump.

Fig. 2 is an end View, the upper half having the cover removed, and thecrank pin, one of the cylinders and its piston shoe being shown insection; in the lower half, the right-hand side is a section on the line2-2 of Fig. 1.

Fig. 3 is a cross-section on a larger scale, showingi the driving crankor eccentric pin, one of the pump pistons being shown'with its shoefitting against the rotatable bearing ring.

Fig. 4 is a corresponding section on an axial plane of the Crank oreccentric pin.

Figs. 5 and 6 are perspective views of the inner end of a pistonand ofthe co-operating shoe respectively.

As illustrated in Figs. 1 and 2, the pump comprises seven cylinders H,spaced evenly around the axis of the pump body |2 and shaft [3, whichlatter drives the pistons |4 in these cylinders by means of shoes |5engaging with a bearing ring IG rotatably mounted on the crank oreccentric pin l'l. The cylinders, which are preferably of square orrectangular section externally ,(as seen in the case of the lowermostcylinder I l in Fig. 1) areyeach provided with a lateral spigot-likehollow projection |8 'at right angles to the axis of the respectivecylinder; each projection IB is engaged in a circular hole or socket |9in the pump body |2, parallel von the Vshaft [3, the projection thusserving to locate the respective cylinder in its radially spacedposition and also to transmit to the pump body the thrust on thecylinder due to pumping action.

The cylinders are clamped in place by means of yoke-pieces 20, eachfitted upon a stud 2| located between two adjacent cylinders, theextremities 22 of each yoke bearing upon two cylinders and its middleportion being apertured at 23' with a part-spherical seating 24 engagedby a correspondingly shaped nut 25. The yokes 20 are arranged towardsthe head ends of the cylinders l, their studs 2| being spaced upon apitch circle of approximately the same radius as that of the circle' onwhich the sockets [9 are spaced. In order to prevent the cylinders frommoving sideways, that is, out of thev radial position, by swinging upontheir projections IB, the crank-ends of the cylinders are arranged tofit between guiding projections in the pump body; for example, theseprojections may be afforded by an annular flange 26 at the innerperiphery of the flat face 21. on the pump body againstwhich thecylinders are clamped, the fiange being notched or slotted outat'appropriate regular intervals to form recesses 28 into which thecylinders fit snugly so that they are held in the correct radialposition by the projecting parts of the flange ,left between th notches.f

ties of two yokes 20 and two ports in thesamecylinder at degrees oneither side of the first, the two latter ports being thus locatedbetween the yokes 20 and the fiat face 21 againstwhich the cylinders areclamped.

Nonreturn or delivery valve seats 30 are arranged upon the spigot-likeprojections |8,'which communicate internally with the respective cylinvders (as seen in Fig. 1, in the case of the upper-`l most cylinder); thenon-return valve 3|, located in the hole or socket 19, is pressed uponits seating 30 by a coiled spring 32 centred by a peg or stud 33 mountedin the opposite end of the socket, the Valve 3| being provided with astem or vanes 34 acting as guide in the interior of the spigot-likeprojection 18. The several sockets 19, spaced around the pump body,communicate with a circular duct 35 leading to a common outlet 36; thelatter is provided by a hollow boss 31 on the end of the pump body,located above a central inlet boss 36 leading to the interior of thebody in alignment with the driving shaft l3.

An end bearng 39 for the driving shaft is inserted in a housing 49within the notched annular fiange 26, suitable ducts or spaces 4| beingprovided around the housing to allow the entrance of liquid from theinlet boss 38 into the chamber where the crank or eccentric pin l1revolves, so that the liquid may reach the cylinder inlet ports 29.Another bearng 42 for the shaft l3is housed in a cover 43 which fitsover the cylinders and engages a rabbeted surface 44 on the exterior ofthe pump body; the shaft extendingv through this bearing is packed bysuitable glands or the like at 45 in the center of the cover, itsprojecting end being splined or otherwise adapted to receive the drive.The cover 43 is shown as provided' with a shouldered flange or facing 46to allow of bolting the entire pump to the driving means, for example anaircraft engine.

The cover 43 is held in place upon the pump body by utilizing the studs2| which clamp the cylinder yokes 20 in place; for this purpose, thestuds are reduced in diameter at 41, beyond the threaded portionsengaged by the yoke-clamping nuts 25, the reduced portionsbeingscrew-threaded to receive sleeved Cap-nuts 48 fitting in holes 49in the cover. This reduction in stud diameter will ensure that when theCap-nuts 43 are tightened, there is no risk of reducing the tension onthe nuts 25 holding the cylinder-yokes in place to any serious extent.When the pump is closed, these nuts 25 are prevented from looseningunder vibration by a reduction of the internal diameter of the pumpcover 43 adjacent to the nuts so that the latter cannot turn, their flatsides being engaged by internal faces of the cover.

The cover 43 may include an air venting hole 50 at its highest point,this hole being normally occupied by a screw-plug a drain for removal ofliquid leaking through the glands at 45 may be provided between two ofthe cap-nuts 48, for example by a radial or inclined hole 52 leadinginto the tunnel 53 which houses the glands, the said hole being drilledthrough a web 54 connecting the outside of the tunnel tov the inside ofthe fiange 46.

The number of cylinders employed in the pump maybe as desired;preferably a prime number is employed, seven cylinder being shown in theconstruction illustrated.

The coupling between the driving crank or eccentr'ic I1 and the severalpistons or plungers |4, by means of the shoes I 5 retained by rings 55,must be designed to suit the standard of performance required from thepump; the form of coupling shown in Fig's. 1 and 2 is particularlysuitable for a pump of this kind where high performance is desired.

In this coupling device, as shown on a larger scale in Figs. 3 to 6inclusive, each of the pump pistons 4, of which only one is shown, hasdirect egagement with the respective shoe |5 through a concave surface56 on the inner end of the piston fitting against a convex surface 51 onthe shoe at the middle of its length, this middle portion of the shoebeing of crescent section, as seen in Fig. 3. The pumping thrust is thuscarried by the mating pair of arcuate surfaces 56, 51 in contact withone another. The piston also has direct engagement withithe shoelthroughother arcuate surfaces, concentric withv the surfaces 56, 51, andcarrying in contact with one another the return thrust which occurs uponthe suction or intake stroke of the piston; these return-thrust bearngsurfaces comprise a convex surface 58 on each side of .thel piston.mating with a concave surface 59 upon the shoe.

As seen more clearly in Figs. 5 and 6, the return-thrust'bearingsurfaces 58, 59 are provided by two arcuate Shoulders 60 formed uponopposite sides of the piston |4, and by two radial wings BI spacedtowards opposite ends of. the shoe 15; in the operative position, thepiston fits between the two wingsl and has its shoulders 69 overlappedby arcuate projections 62 left by recessing or undercutting the adjacentfaces of the wings. The Shoulders 69 provide the arcuate surfaces 53concentric with the concave surface 56 on the inner end of the piston,while the projections 62 provide the mating surfaces 59 concentric withthe outer surface 51 of the middle portion of the shoe.

Beyond the wings 5|, andv towards each end, the shoe is formed with aconvex' outer surface 53, concentric with' the concave inner surface 64which engages upon the rotatable bearng ring 16;, the convex surfaces 63receive the retainingjrin'gs which engage the several shoes of't-h'epump, coupling; At, each end of the shoe, a segmental flan'ge' B6'projects radially outwards, similarly to the wings 6| but notnecessarily to the'same' radial extent, the two flanges 66 serving tomaintain the retaining rings 55 in place within the part-grooves formedbetween. these fianges 69 and the adjacent wings 6|;

In order to simplify'and cheapen manufacture, it is desirable that thediameter of the shouldered end. of the piston 14 should not exceedthat'of the piston as a whole; with this object in view, the Shouldersare preferably formed by milling or otherwise producing two recesses 61on opposite sides of the piston, at a short distance from its inner end,one face of the recess constituting the return-thrust bearng surface 58,concentric with the concave surface 56 and parallel thereto in thedirection of their common axis. The radial distance between theseconcentric surfaces, 56,` 58 will represent the depth. of the Shoulders69, which in turn is made equalto the radial depth of the recess orundercut below the projections 62 of the Wings.

The Shoulders 69 are preferably made with two parallel flats 68, of alength equal to about half the diameter of the piston, these, fiatshaving a suitable working clearance from the interior faces of therecesses or undercuts in the wings; the axial length of the matingsurfaces 56, 51 will then be slightly less than the diameter of thepiston, as seen in Fig. 4, these surfaces being provided at the middleof the length of the shoe, but the contacting surfaces of the shoe l5and bearng ring |5 extend for the entire length of the shoe.

What I claim is:

l. A pump -comprising a casing, a driving shaft mcunted in said casing,a plurality of pumping cylinders spaced radially around said shaft,pistons reciprocable in rsaid cylinders, eccentric acarkov means forreciprocating said pistons by operation of .said shaft, each of saidcylinders having an inlet port uncovered by the respective pistontowards the end of its admission stroke, and a delivery valve for eachof said cylinders, each of said cylinders including a lateralspigot-like projection engaging in a socket in said casing to locate therespective cylinder spaced radially from said shaft and to transmit thepumping thrust of said cylinder directly to said casing, and each ofsaid delivery valves having its seat upon the sp'igo-t-like projectionof the respective cylinder.

2. A pump comprising a casing, a driving shaft mounted in said casing, aplurality of pumping cylinders spaced radially around said shaft,pistons reciprocable in said cylinders, eccentric means forreciprocating said pistons by operation of said shaft, each of saidcylinders havingl an inlet port uncovered by the respective piston to-Wards the end of its admission stroke, and 'a delivery valve for each ofsaid cylinders, each of said cylinders including a hollow lateralprojection engaging in a hole in said casing to locate the respectivecylinder spaced radially from said shaft and to transmit the pumpingthrust of said cylinder directly to said casing, and each of saiddelivery valves being arranged in the lateral projection of therespective cylinder.

3. A pump comprising a casing, a driving shaft mounted in said casing, aplurality of pumping cylinders spaced radially around said shaft,pistons reciprocable in said cylinders, eccentric means forreciprocating said pistons by operation of said shaft, each of saidcylinders having an inlet port uncovered by the respective pistontowards the end of its admission stroke, and a delivery valve for eachof said cylinders, each of said cylinders including a lateralspigot-like projection formed integrally with it, said projections'engaging in spaced holes in said casing to locate said cylinders spacedradially from said shaft and to transmit the pumping thrusts of saidcylinders directly to said casing, and said projections having seats forsaid delivery valves arranged there- 4. A pumpl comprising a casing, adriving shaft mounted in said casing, a plurality of pumping cylindersspaced radially around said shaft, pistons reciprocable in saidcylinders, eccentric means for reciprocating said pistons by operationof said shaft, each of said cylinders having an inlet port uncovered bythe respective piston towards the end of its admission stroke, and adelivery valve for each of said cylinders, each of said cylindersincluding a hollow lateral spigotvlike projection formed integrally withit, said projections engaging in spaced holes in said casing to locatesaid cylinders spaced radially from said shaft and to transmit thepumping thrusts of said cylinders directly to said casing, said deliveryvalves being mounted co-axially with the respective projections andholes, and seats for said delivery valves upon said projections.

5. A pump comprising a casing, a driving shaft mounted in said casing, aplurality of pumping cylinders spaced radially around said shaft,pistons reciprocable in said cylinders, eccentric means forreciprocating said pistons by operation of said shaft, each of saidcylinders having an inlet controlled by the reciprocation of therespective piston, a lateral spigot-like projection from each of saidcylinders, said projections engaging in spaced holes in said casing,means for clamping said cylinders in place, said clamping meanscomprising yokes each engaging two'of said cylinders and screwed membersconnecting said yokes to the said casing, and a delivery valve for eachof said cylinders, said delivery valve being seated upon the respectiveprojection.

6. A pump comprising a casing, a driving shaft mountedrini said casing,a plurality of pumping cylinders spaced radially around said shaft,pistons reciprocable in said cylinders, eccentric means forreciprocating said pistons by operation of said shaft, each of saidcylinders having an inlet controlled by the reciprocation of therespective piston, a lateral spigot-like'projection from each of saidcylinders, said projections engaging in spaced holes in said casing,means for clamping said cylinders in place, said clamping meanscomprising yokes each engaging two of said cylinders and screwed membersconnecting said yokes to said casing, guide surfaces arranged in spacedpairs Within said casing, each of said p cylinders fitting between theguide surfaces of one pair thereof, and a delivery Vvalve for each ofsaid cylinders, said delivery valve being seated upon the respectiveprojection.

7. A pump comprising a casing, a driving shaft mounted in said casing, aplurality of pumping cylinders spaced radially around said shaft,pistons reciprocable in said cylinders, eccentric means forreciprocating said pistons by operation of said shaft, each of saidcylinders having an inlet controlled by the reciprocation of therespective piston, a lateral spigot-like projection from each of saidcylinders, said projections engaging in spaced holes in said casing,means for clamping said cylinders in place, said clamping meanscomprising yokes each engaging two of said cylinders and screwed membersconnecting said yokes to said casing, a detachable cover for saidcasing, said cover being normally held in place by said screwed members,and a delivery valve for each of said cylinders, said delivery valvebeing seated upon the respective projection.

8. A pump comprising a casing, a driving shaft mounted in said casing, aplurality of pumping cylinders spaced radially around said shaft,pistons reciprocable in said cylinders, eccentric means forreciprocating said pistons by operation of said shaft, each of saidcylinders having an inlet controlled by the reciprocation of therespective piston, a lateral spigot-like projection from each of saidcylinders, said projections engaging in spaced holes in said casing,means for clamping said cylinders in place, said clamping meanscomprising yokes each engaging two of said cylinders, screwed studsengaged in said casing and nuts screwed upon said studs for connectingsaid yokes to said casing, a detachable cover apertured to pass oversaid studs into the vicinity of said nuts, said cover normally enclosingsaid cylinders and clamping means, and said cover having internal facesadapted to lock said nuts upon said studs, means for holding said coverin place upon said casing by engagement with said studs, and a deliveryvalve for each of said cylinders.

9. A pump comprising a casing, a driving shaft mounted in said casing, aplurality of separate pumping cylinders spaced radially around saidshaft, said cylinders including flat and parallel external surfaces,pistons reciprocable in said cylinders, eccentric means forreciprocating said pistons by operation of said shaft, each of saidcylinders having an inlet controlled by the reciprocation of therespective piston, a lateral spigot-like projection from each of saidcylinder, saidprojections engaging, in spaced holes a insadzcasing,means fonc'lampingvsaid cylinders inpIae, saidjclamping means'comprisingyokes eachengaging twoof'saidfcylinders and screwed members connectngsaid yokes to said casing, guide surface'arr'angedv inspaced pairsWithin saidcasing, the guide surfaces of each pair being parallel, eachof ,saidV cylinders having its parallel external surfacesfitted betweenthe parallel guidel surfacesv engaging. with said cylinders to locate,them, radially'with respect to the axis of said casing, and: thecombination of said projections and guidesurfaces locatingsaid cylindersin positionsfspaced radially around the aXis of said casing. i

11 Ina radial pump of the Character' set forth, a plurality of separatecylinders each provided 8; with an integral lateral projection, a casingformed' with lrloles` spa-ced on a `circle, each ofsaidprojectionsengaged in one of said holes, a crcular` duet in saidcasing, all of said holes communi'cating with said duet, non-returnvalves arrangedupon said projections and controlling delivery from therespective cylinders to said duet, an outlet from said duct, and guidesurfaeswithinsaid casing, said 'guide surfaces engaging wthsaidcylinders to locate them radially Withfrespet to the. axis v of saidcasing.

' GEORGE J OSEPI-I TRAPP.

REFERNCES CIfI'ED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Lskey Jan. 15, 1946

